Evaluation of the Antioxidant and Antimicrobial Properties of Pumpkin Pulp During Storage Through the Ultrasonication Process

Abstract

Pumpkin (Cucurbita maxima) is a seasonal fruit and it contains large amounts of bioactive compounds, including phenolic compounds, carotenoids, and anthocyanins, which lower the risk of cancers and prevent osteoporosis and hypertension. However, conventional pasteurization reduces the nutrient content of fruits and results in a loss of organoleptic properties. Food processing industries are exploring alternatives to thermal treatment (TT) due to the increasing demand for safe, high-quality, and minimally processed pumpkin pulp. The outcomes of thermal treatment and ultrasonication (US) on the overall quality of pumpkin pulp were examined in this study. Six treatments were used in the preparation of pumpkin pulp: T₀ (control), T₁ (TT at 90 °C for 2 min), and T₂ to T₅ (US of 37 kHz frequency for 5-20 min). Statistically analyzed data showed a significant increase in total phenolic contents (TPC) and total flavonoid contents (TFC) in US-treated samples (216 to 222 mg GAE/100 g) and (7.53 to 12.9 mg CE/100 g) respectively. In contrast, a significant decrease in microorganisms was found in all US-treated samples. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays increased significantly in US-treated samples (29.20 to 33.71%), (0.92 mg TE/g to 1.36 mg TE/g), and (4.52 mg TE/g to 5.15 mg TE/g) respectively. Nevertheless, a significant rise in ascorbic acid levels was observed in the T₅ sample (15.48 mg/100 g). All US-treated samples showed significantly fewer losses in bioactive compounds and effectively decreased microbial load during storage as compared to thermal treatment. This research indicated that the US T₅ showed the best results and demonstrated an ability to enhance the overall quality of pumpkin pulp, which can be effectively utilized for processing in industries.